Three years after Amsterdam, Harold and Kumar are no longer best buds, with the former married to Maria (Paula Garces) and desperate to curry favor with her Christmas-obsessed father, Mr. Perez (Danny Trejo), and the latter smoking up a storm in the apartment the two friends used to share. When Kumar receives a package addressed to Harold, he takes it over to his house and accidentally burns down Harold's new Christmas tree -- a prized Douglas fir that Mr. Perez grew himself. Trailed by Kumar's new friend Adrian (Amir Blumenfeld) and Harold's sycophantic work buddy Todd (Thomas Lennon), who has his daughter with him, the foursome set off into the city trying to replace the tree.

Somehow, everything in the title -- Harold & Kumar, 3D, and Christmas -- are the things that bring the movie down. The Christmas elements are just lame: a claymation gag that's been covered by "It's Always Sunny" and "Community" in the time since the movie was written (and maybe even before that in Elf), and a big finale that continues the series' complete drift from reality. The 3D is even bigger nuisance, winking at the audience -- isn't it funny you're watching a 3D movie? -- by throwing every other object straight into the camera with the "aid" of terrible CGI. It might've been sort of amusing if the 3D was any good, but it's flat and lifeless -- I briefly hoped scenes where the characters were stoned would be in 3D and the other scenes would be in 2D, but it's just lame post-conversion techniques rather than a style.

Most disappointing, though, is the way the film lets down its characters. Once again, Kumar's conflict is about embracing his natural talent for medicine, a story that's not only been resolved twice already, but one that the film doesn't even care about. In the original, Kumar's skills had enough weight to work as both comic exaggeration and character development, but his "big moment" in this film is so undercut by the direction and circumstances that he might as well wave a magic wand. Similarly, Harold has regressed into his old, stick-in-the-mud ways, and even if it makes sense Harold would be afraid of his father-in-law, and Cho plays his moments well, it's still overly familiar territory. The film also finds new reasons to put them at each other's throats -- aren't Harold and Kumar supposed to be friends? -- and although starting with them apart is intriguing, the script does nothing with it. Why not, say, have Harold be the slacker and Kumar the adult this time? Anything to genuinely shake up the formula.

The movie does have its moments: once again, Neil Patrick Harris steals the show with a willingness to do anything to his image under the guise of the fictionalized "Neil Patrick Harris" he plays in the movies, including turning his homosexuality into a scheme for the sake of his career (while the movie sort of subversively uses it to sneak a genuine gay kiss into a mainstream Hollywood comedy), and illustrating his wild journey into the afterlife. The social satire that informed the first two is almost absent here, although there are a couple of good gags about gangsta grills and Mafia Wars. There's also a very funny must-have gift item I won't spoil (someone, please invent this for real), and Danny Trejo is absolutely wonderful as Maria's dad -- a sight gag involving his character that comes at the end of one of the movie's funniest sequences is the highlight of the entire picture. Too bad the rest is a disappointment. Although the picture is ostensibly about maturity, with 3D Christmas, the Harold & Kumar series has fully regressed from stoner spoof to stoner stupidity.